US5953548A - Inverted galilean type variable magnification zoom finder - Google Patents
Inverted galilean type variable magnification zoom finder Download PDFInfo
- Publication number
- US5953548A US5953548A US08/864,966 US86496697A US5953548A US 5953548 A US5953548 A US 5953548A US 86496697 A US86496697 A US 86496697A US 5953548 A US5953548 A US 5953548A
- Authority
- US
- United States
- Prior art keywords
- field frame
- lens
- zoom finder
- variable magnification
- type variable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/14—Viewfinders
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/144—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
- G02B15/1441—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive
- G02B15/144105—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive arranged +-+-
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/14—Viewfinders
- G02B23/145—Zoom viewfinders
Definitions
- This invention relates to a variable magnification zoom finder chiefly used in a compact camera, and in particular, to an inverted Galilean type variable magnification zoom finder.
- FIGS. 1A-1C An example of an optical system of a conventional virtual image mode variable magnification zoom finder for compact cameras is shown in FIGS. 1A-1C.
- the optical system of this finder includes a first fixed lens 1, a second fixed lens 2, and a third fixed lens 3 which are arranged on an optical axis a; a moving lens 4 disposed between the first fixed lens 1 and the second fixed lens 2 to be movable along the optical axis a; and a fixed field frame 5 disposed such that it is stationary on the side of a pupil b of the first fixed lens 1.
- a height of a chief ray from the optical axis a at the fixed field frame 5 has a minimum h 1 where the moving lens 4 is located at a wide-angle position (FIG. 1A).
- a height h 2 of the chief ray from the optical axis a at the fixed field frame 5 is progressively increased and reaches a maximum h 3 where the moving lens 4 is located at the telephoto position (FIG. 1C).
- the conventional virtual image mode variable magnification zoom finder is merely designed so that the single fixed field frame 5 is placed to accommodate a change in magnification of the finder.
- an angle made by the optical axis with the chief ray emerging from an eyepiece system and reaching a pupil is set to be constant in order to make a field factor constant over the range from the wide-angle position to the telephoto position.
- a field area is determined by the single field frame 5, and thus the height of the chief ray from the optical axis a at a lens (or a lens unit) is varied in accordance with the magnification change from the wide-angle position to the telephoto position (namely, as shown in FIGS. 1A-1C, h 1 ⁇ h 2 ⁇ h 3 ). For this reason, the angle of the chief ray reaching the pupil does not become constant and unwanted light reaches the pupil, causing the problem of hindering the determination of the composition of photography.
- FIGS. 2A-2C show an example of the albada type variable magnification zoom finder.
- This albada type finder includes a first fixed lens 6 and a second fixed lens 7 which are arranged on the optical axis a; a half mirror 8 interposed between the first fixed lens 6 and the second fixed lens 7, having a half mirror surface 8a; and a moving lens 9 movable along the optical axis a between the first fixed lens 6 and the half mirror 8.
- the albada type variable magnification zoom finder has the advantage that when an optical frame c is attached to the eyepiece system, a photographing area becomes clear and the determination of the composition can be accurately made.
- the albada type variable magnification zoom finder which imperatively requires the half mirror surface 8a to be situated at an arbitrary place, has the problem that the transmittance of the entire finder system is reduced and as a result, the entire visual field becomes dark, detrimental light such as ghost attributable to the half mirror surface 8a is produced, or a rise in manufacturing cost is caused because of the placement of the half mirror.
- Japanese Utility Model Preliminary Publication No. Sho 60-128329 discloses an inverted Galilean type finder in which two field frames of different sizes are provided and alternately placed on the optical axis, thereby allowing the magnification to be changed.
- This inverted Galilean type finder requires a complicated mechanism for alternately inserting the two field frames in the optical axis and thus is not necessarily suitable for the latest camera requiring compact design.
- variable magnification zoom finder notably an inverted Galilean type variable magnification zoom finder, which can bring about a proper field area over the range from the wide-angle position to the telephoto position without using the arrangement of the albada type variable magnification zoom finder.
- the inverted Galilean type variable magnification zoom finder is constructed so that a field frame is provided and variable in accordance with the magnification change.
- the field frame is designed to be movable along the optical axis.
- a moving lens or a lens unit
- the position of the field frame is shifted to thereby secure a proper field area with respect to a photographing area, no matter whether the focal length of the photographing lens optical system corresponds to the wide-angle position or the telephoto position.
- the field frame can be designed so that it can be moved integrally with a lens or lens unit, or independently of it.
- a fixed field frame is disposed at an arbitrary place, the height of the chief ray from the optical axis at the telephoto position and a movable field frame constructed integrally with a moving lens is determined, the height of the chief ray from the optical axis at the wide-angle position is determined by the arrangement in the finder optical system.
- the optical system which is simple in arrangement and has the same function as in the albada type variable magnification zoom finder can be obtained.
- the positions of the field frames at the wide-angle and telephoto positions may be reversed, depending on the lens type.
- the field frame may be constructed by mechanical means or may also be constructed in such a way that paint is applied to the side or end surface of a lens, or a treatment may be carried out such that the lens has a diffusing surface.
- FIGS. 1A, 1B, and 1C are schematic views showing operating conditions of a conventional inverted Galilean type variable magnification zoom finder
- FIGS. 2A, 2B, and 2C are schematic views showing operating conditions of a conventional albada type variable magnification zoom finder.
- FIGS. 3A, 3B, and 3C are schematic views showing operating conditions of an inverted Galilean type variable magnification zoom finder of an embodiment in the present invention.
- the inverted Galilean type variable magnification zoom finder in this embodiment includes a first fixed lens 10, a second fixed lens 11, and a third fixed lens 12 which are arranged on the optical axis a and a moving lens 13 disposed to be movable along the optical axis a between the first fixed lens 10 and the second fixed lens 11.
- a fixed field frame 14 is placed on the pupil side of the first fixed lens 10, and a field frame 15 is attached to the surface of the moving lens 13 facing the pupil. That is, the field frame 15 can be moved, together with the moving lens 13, along the optical axis a.
- the moving lens 13 in the finder optical system is located on the object side, namely closest to the first fixed lens 10.
- the moving lens 13 is moved from the object side toward a pupil 16, namely from the first fixed lens 10 toward the second fixed lens 11.
- the moving lens 13, as shown in FIG. 3C is located on the side of the pupil 16, namely closest to the second fixed lens 11.
- H 1 the height of the chief ray from the optical axis a at the fixed field frame 14 when the moving lens 13 is located at the wide-angle position
- H 2 the height of the chief ray from the optical axis a at the fixed field frame 14 when the moving lens 13 is located midway between the wide-angle position and the telephoto position
- H 3 the height of the chief ray from the optical axis a at the fixed field frame 14 when the moving lens 13 is located at the telephoto position
- the height of the chief ray from the optical axis a at the fixed field frame 14 is minimized when the moving lens 13 is located at the wide-angle position, is progressively increased when the moving lens 13 is moved from the wide-angle position toward the telephoto position, and is maximized when the moving lens 13 is located at the telephoto position.
- T 1 denotes the height of the chief ray from the optical axis a at the moving field frame 15 where the moving lens 13 is located at the wide-angle position (FIG. 3A)
- T 2 the height of the chief ray from the optical axis a at the moving field frame 15 where the moving lens 13 is located midway between the wide-angle position and the telephoto position (FIG. 3B)
- T 3 the height of the chief ray from the optical axis a at the moving field frame 15 where the moving lens 13 is located at the telephoto position
- the height of the chief ray from the optical axis a at the moving field frame 15 is maximized when the moving lens 13 is located at the wide-angle position, is progressively decreased as the moving lens 13 is moved from the wide-angle position toward the telephoto position, and is minimized when the moving lens 13 is located at the telephoto position.
- the field area at the wide-angle position is determined by the behavior of the moving field frame 15 intercepting rays of light outside the field area
- the field area at the telephoto position is determined by the behavior of the fixed field frame 14 intercepting rays of light outside the field area.
- a proper field area can be obtained with respect to the photographing area, no matter whether the focal length of the photographing lens optical system corresponds to the wide-angle position or the telephoto position.
- the above behavior may be reversed, depending on the lens type, but in this case, it is only necessary to interchange the field frames 14 and 15.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Astronomy & Astrophysics (AREA)
- Viewfinders (AREA)
- Lenses (AREA)
Abstract
Description
H.sub.1 <H.sub.2 <H.sub.3
T.sub.1 >T.sub.2 >T.sub.3
Claims (9)
H1<H2<H3
T1>T2>T3
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8136911A JPH09318994A (en) | 1996-05-30 | 1996-05-30 | Inverted galilean zoom variable power finder |
JP8-136911 | 1996-05-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
US5953548A true US5953548A (en) | 1999-09-14 |
Family
ID=15186462
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/864,966 Expired - Fee Related US5953548A (en) | 1996-05-30 | 1997-05-29 | Inverted galilean type variable magnification zoom finder |
Country Status (2)
Country | Link |
---|---|
US (1) | US5953548A (en) |
JP (1) | JPH09318994A (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60128329A (en) * | 1983-12-15 | 1985-07-09 | Fuji Xerox Co Ltd | Background density detecting device |
US5300977A (en) * | 1992-09-01 | 1994-04-05 | Eastman Kodak Company | Zoom viewfinder with fixed size moving window |
US5404189A (en) * | 1993-11-30 | 1995-04-04 | Eastman Kodak Company | Panoramic viewfinder mask |
-
1996
- 1996-05-30 JP JP8136911A patent/JPH09318994A/en not_active Withdrawn
-
1997
- 1997-05-29 US US08/864,966 patent/US5953548A/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60128329A (en) * | 1983-12-15 | 1985-07-09 | Fuji Xerox Co Ltd | Background density detecting device |
US5300977A (en) * | 1992-09-01 | 1994-04-05 | Eastman Kodak Company | Zoom viewfinder with fixed size moving window |
US5404189A (en) * | 1993-11-30 | 1995-04-04 | Eastman Kodak Company | Panoramic viewfinder mask |
Also Published As
Publication number | Publication date |
---|---|
JPH09318994A (en) | 1997-12-12 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: OLYMPUS OPTICAL CO., LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MORI, AKIRA;REEL/FRAME:008682/0759 Effective date: 19970325 |
|
AS | Assignment |
Owner name: OLYMPUS OPTICAL CO., LTD., JAPAN Free format text: (ASSIGNMENT OF ASSIGNOR'S INTEREST) RE-RECORD TO CORRECT THE RECORDATION DATE OF 4/23/97 TO 5/29/97, PREVIOUSLY RECORDED ON REE 8682, FRAME 0759.;ASSIGNOR:MORI, AKIRA;REEL/FRAME:008768/0040 Effective date: 19970325 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
REMI | Maintenance fee reminder mailed | ||
LAPS | Lapse for failure to pay maintenance fees | ||
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20070914 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |